At present, China's air-conditioning system has several types of cold and heat sources mainly as follows: 1. single cold air conditioning host with cooling tower and boiler air conditioning system; 2. various types of heat pump air conditioning system; 3. lithium bromide air conditioning system; 4. ice storage with other heat source air conditioning systems. Among them, in the summer, the single cold air conditioning host is used for refrigerating and cooling tower is used for radiating and in winter, the boiler is used for heating, which has the advantages that the application is flexible, it is not subject to constraints from project scale, and it has low initial investment and thus can be widely used in various types of buildings, but has the defect that the apparatus has idle time, the overall efficiency is not high, the boiler burns fossil energy and the exhaust has pollution. Various types of heat pump air conditioning system include air source heat pump, water source heat pump, ground source heat pump, sewage source heat pump. Among them, air source heat pump using outdoor air as a cold source is the most simple application with the advantages that it can be used both in winter and summer, the initial investment is low, it is a flexible application, but with the defect that the operation state is unstable, especially in the most adverse winter and summer environment, it has low efficiency, it maybe frost in winter and needs electric auxiliary heating for normal use. Water source heat pump use surface water and groundwater as the source of cold and heat sources in winter and summer, with the advantages that the operation is safe and reliable, the annual operation efficiency is high, but with the defect that it needs a stable and reliable water source near the building so that it can be used, and the current groundwater exploitation has been limited. Ground source heat pump has the advantages that the perennial operation condition is stable, the operation efficiency is high, the project operating costs is low, but has the defect that it needs large pre-construction land area, needs drilling and buried-pipe treatment, the project early investment is high, it is subjected largely to the geographical environment and geological conditions constraints. Lithium bromide air conditioning system using thermal energy as unit energy can also provide hot and cold water at the same time, with the advantages that the operational power consumption is low, waste heat can be used as energy, but with the defects that it requires large project volume, annual attenuation is larger, operating costs is higher and the management is inconvenient. Ice storage stores cooling capacity in the form of ice using low-cost electricity at night, releasing it when it needs cold supply during the day, with the advantages that the refrigerating temperature is low and stable, air conditioning effect is good, the operation is economic and simple, but with the defects that the initial investment is high, other heat source is needed for heating in the winter.
Comparing above conventional air conditioning cold and heat source, single cold air conditioning host with cooling tower and boiler air conditioning system is the most common and most widely used due to its outstanding advantages and occupies a large proportion in China's large and medium-sized building air conditioning system. In the summer, the single cold air conditioning host uses the compressor to compress the refrigerant, extract the heat of the chilled water in the user system and transfer it to the cooling water, then distribute it to the air by the cooling tower and thus continuously provide the user system with cooling capacity. In winter, boiler is used to supply water for heating to the user system, so as to provide heat for the user air conditioning system. In the south of the Qinling Mountains and the Huaihe River, there is no central heating in winter, and often a single building or building groups use central air conditioning system for heating. During the building using air conditioning period, the time period when the outdoor temperature is less than five degree is less, the boiler output is not full. In this system, the entire heating season uses boilers for heating. But the boiler combustion efficiency is low and the required fossil energy is non-renewable energy. In the combustion process, the exhaust contains sulfide, nitrides and other, substances causing environmental contamination. Every winter, the formation of air pollution and haze climate caused by the combustion of various boilers do great harm to human health. Therefore, boiler burning in the winter directly causes environmental pollution and energy waste, while in the winter single cold air conditioning host and cooling tower stop operating, resulting in equipment idle.
In the winter, the wet and cold air still has a certain temperature. For the environment with the temperature lower than the wet and cold air temperature, this wet and cold air is still an infinite heat source and the heat therein can be absorbed in a certain way. At the same time, solar thermal heat is pollution-free, environmentally friendly and efficient heat energy, and during the period in which winter sunshine is strong, the solar energy has not been applied in this air conditioning system, resulting in a great waste of energy.
Therefore, if the single cold air conditioning host and cooling tower are to be transformed so that during the period when the winter ambient temperature is higher than five degrees, the heat in the air is absorbed by using a single cold machine with cooling tower, making full use of solar thermal heat to form an all-weather solar air conditioning system to provide the user with air conditioning heating, which can greatly reduce the time of using boiler. At the same time, the cooling backwater in the single cold air conditioning host is heated by making full use of solar energy, improving the temperature of inflow water of the single cold machine and thus improving heating efficiency of the single cold machine. In this way, the single cold air conditioning host which is idle originally can be used as a high-efficiency heating host, while the pollution-free renewable energy is used, saving a lot of costs and reducing environmental pollution, and bringing a very important economic value and social value.